The present invention relates to an improvement in the processes for manufacturing semiconductor devices, particularly in the sputter etching processes.
More particularly, the present invention relates to an improvement in the processes of sputter etching particularly suitable to embody structures on monocrystalline materials, specifically on composite semiconductors suitable to embody detectors of infra-red radiation.
The usual used techniques for shaping structures on materials in massive form, particularly monocrystalline materials, are chemical etching and electrochemical etching.
These conventional techniques suffer from various drawbacks, e.g. underetching of the material, formation of point-like pitting, attack along crystallographic preferential directions and preferential attack along dislocation lines and other imperfections of the crystal lattice.
When the material is removed by sputter etching, these drawbacks will not occur. However, other problems arise, generally attributed to cross contamination between the processed material and the masking material.
This phenomenon occurs mainly when a processed material which is etched at a relatively high speed is exposed to surface contamination due to back scattering of the masking material which will be etched at a relatively low speed.
This contamination produces characteristic cone formations on the processed material, causing surface roughness, discolouring, slowing of the etching speed and non repeatability of the process.